US2874412A - Apparatus and process for centrifugal molding of articles from thermoplastic materials which exhibit substantial volumetric shrinkage - Google Patents

Apparatus and process for centrifugal molding of articles from thermoplastic materials which exhibit substantial volumetric shrinkage Download PDF

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Publication number
US2874412A
US2874412A US339846A US33984653A US2874412A US 2874412 A US2874412 A US 2874412A US 339846 A US339846 A US 339846A US 33984653 A US33984653 A US 33984653A US 2874412 A US2874412 A US 2874412A
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United States
Prior art keywords
mold
piece
plug
tube
solidification
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Expired - Lifetime
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US339846A
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English (en)
Inventor
Norbert A Flemming
Eugene E Montross
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Polymer Corp
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Polymer Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to NL99227D priority Critical patent/NL99227C/xx
Priority to FR65927D priority patent/FR65927E/fr
Priority to FR1047775D priority patent/FR1047775A/fr
Application filed by Polymer Corp filed Critical Polymer Corp
Priority to US339846A priority patent/US2874412A/en
Priority to DEP11425A priority patent/DE1101750B/de
Application granted granted Critical
Publication of US2874412A publication Critical patent/US2874412A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C41/00—Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor
    • B29C41/34—Component parts, details or accessories; Auxiliary operations
    • B29C41/38—Moulds, cores or other substrates
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
    • B29B13/00—Conditioning or physical treatment of the material to be shaped
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C41/00—Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor
    • B29C41/02—Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor for making articles of definite length, i.e. discrete articles
    • B29C41/04—Rotational or centrifugal casting, i.e. coating the inside of a mould by rotating the mould
    • B29C41/042—Rotational or centrifugal casting, i.e. coating the inside of a mould by rotating the mould by rotating a mould around its axis of symmetry
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C41/00—Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor
    • B29C41/34—Component parts, details or accessories; Auxiliary operations
    • B29C41/42—Removing articles from moulds, cores or other substrates
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2077/00—Use of PA, i.e. polyamides, e.g. polyesteramides or derivatives thereof, as moulding material
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S264/00—Plastic and nonmetallic article shaping or treating: processes
    • Y10S264/56—Processes of molding lactams

Definitions

  • This invention relates to the manufacture of articles from molten materials, particularly thermoplastic materials, more especially the synthetic linear polyamides known to the trade as nylon, and most especially from the high melting polyamides such as polyhexamethylene adipamide, polyhexamethylene sebacamide and polyepsilon aminocaproicacid (caprolactam).
  • the invention is particularly concerned 'with improved molding apparatus and technique.
  • the present invention has as its primary object the provision of improved method and apparatusfor accurately and consistently forming pieces which are uniform and symmetrical about their central axes, and is particularly useful in centrifug'ally casting tubular pieces, for instance, pieces having cylindrical inside and outside surfaces.
  • Other objects of the invention include provision forp'roduction ofsuch uniform pieces at a relative ly high'rate, with given equipment.
  • This invention is an improvement over the invention disclosed in the application of Louis L. Stott, filed June 8, 1950, Serial No. 166,790, andassigned to the as- This 2,874,412 Patented Fe b. 19 59 tering of the piece being molded with reference to the axis of spinning of the mold. In this way provision is made for forming pieces which are highly uniform and symmetrical about their central axes, as will further appear.
  • Figure 1 is a vertical sectional view of a moldconstructed according to the present invention, this. view illustrating the mold associated with charging equipment, portions of which equipment are shown in outline only;
  • Figure 2 is a longitudinal sectional view of a mold such as shown in Figure 1, this view showing the mold on an enlarged scale as compared with Figure 1, and showing a charge of molten material distributed within the mold as it initially would be during the spinning thereof, and further illustrating the, mold in association with equipment used for spinning; f v
  • Figure 3 is a fragmentary sectional view of the mold of Figure 2 showing the material therein distributed as it would be after completion of solidification; and 1, i
  • Figure 4 is a longitudinal sectional view of a, second embodiment of a mold ofthe present invention.
  • a piece having cylindrical inside and outside surfaces is formed by] first preparing a charged and heated mold comprising a mold cylinder having end closure plugs, then spinning the mold about its longitudinal axis, and cooling the mold and its chargewhile continuing the spinning, until the temperature of both the mold and the charge are brought below the solidification point of the material being molded, whereupon the mold is opened and the solidified cylindrical'piece removed.
  • the mold is mountedfor rotation about its longitudinal axis by means of twofmold supports located generally axially of the mold at the'ie'nds thereof.
  • the mold comprises a cylinder or tube 5, preferably having a nicely finished interior surface, and end plugs 6 and 7 which may. be placed in the tube to substantially close the ends thereof.
  • Plug 6 is shouldered to provide a portion fitting within the main mold cavity, and also. a'flange '8 adaptedto abut the end wall of the tube. Fastening screws 9 may be used to hold it in proper position.
  • Plug 6 further has a centrally located recess 10 which is threaded to receive the threaded end 11 of a rotative mold support 12.
  • annular groove 13 located on the inside face 14 of plug 6. This groove provides a cavity extensionhaving a peripheral surface15 which flares outwardly in 'a direction away from the main mold cavity; that is, surface 15 defining the side of @Ihe groove more remote from the plug rotative axis, is inclined with respect to this axis in such direction that the groove 13 undercuts the edge 16.
  • Surface 15, if extended out of the groove would describe a right circular cone with its axis coincident with the longitudinal mold axis and withits vertex pointing toward the opposite end of the mold tube.
  • Plug ,7 is adapted to be inserted in the other end of the mold tube, this plug also having a portion fitting, within the mold and having a flange 17 abutting the end wall of the mold. Thumb screws 18 are preferably employed to retain the plug 7' in proper positionand also to serve another purpose referred to below.
  • Plug-7 has a central aperture 19 extended therethrough, the outer portion of which is flared as indicated at 20, adapted to be engaged by the tapered end portion 21 of the support 22 for rotatively mounting the mold.
  • the central aperture 19 and its flared portion 20 serve other purposes described below.
  • the inside face 23 of plug 7 is grooved as at 24.
  • the peripheral groove surface 25 flares outwardly in a direction away from the main mold cavity, that is, surface 25 is inclined with respect to the rotative axis in a direction to'cause the groove 24 to undercut the edge 26.
  • the degree of inclination of the surfaces and 25 with respect to the axis of rotation depends on several factors described later.
  • a screw type feeder shown in outline'in Figure 1, may comprise a feed screw (not shown) within a casing 27 having a feed hopper 28 and a delivery pipe 29.
  • the screw and its casing are preferably surrounded by a heating jacket or the like, indicated in outline at 30, and containing electrical or other heating means.
  • the material is fed, preferably in flake or granular form, into the hopper 28 and is thereupon simultaneously advanced by the screw and heated by the jacket 30 so that the material is melted while being advanced.
  • the melted material is discharged through the pipe 29, the nozzle structure 31 and one or more charging nozzles 32.
  • Each charging nozzle has a tapered end portion the purpose of which is described below.
  • a valve 33 is provided for each charging nozzle to regulate the flow of melted material therethrough.
  • Heating means (not shown) may be added if necessary to the nozzle structure and/or the charging nozzles to retard cooling of the material during discharge thereof.
  • the mold tube with the end plugs assembled therewith is placed in a heating chamber 34 adapted to be heated by electrical or other heating'means such as indicated at 35.
  • the thumb screws 18 serve to support the mold by engagement with the upper end of the heating chamber 34.
  • Chamber 34 has a bottom wall 36 supported by an adjustable jack mechanism 37, sothat the entire heating chamber with the mold therein may be raised and lowered with reference to one of the nozzles 32.
  • the end plugs and mold tube are assembled and this assembly may'then be preheated, forinstance by insertion in a heating chamber or furnace, or by immersion in a heating bath.v Although the temperature of preheat fit .of the pieces being formed.
  • the piece to be formed is cylindrical and will occupy only a fraction of the total volume of the mold, the charge will, of course, be substantially less in volume than the total volume of the mold cavity.
  • the mold After charging the mold is removed from association with the charging nozzle and heating chamber and promptly associated with the mold spinning equipment, including rotative supports such as shown at 12 and 22 in Figure 2.
  • the tapered end portion 21 of the support 22 now serves not only to support the mold for spinning but also to close the filling aperture and thereby prevent ingress of air and egress of molten material.
  • the mold is advantageously rotatively driven through the support 12.
  • the molten material is distributed into the form of a cylinder, for instance as illustrated at M in Figure 2.
  • the mold and the charge therein are now cooled, for instance by contact of the air with the outside surface of the mold, while the spinning continues, the temperature being taken down below the solidification point of the material being molded.
  • the cooling action may be augmented by directing a stream of coolant, such as air or water onto the outer surface of the mold.
  • coolant such as air or water
  • the spinning operation should be effected at relatively high rotational speeds, although the speeds may be varied somewhat depending upon the diameter and wall thickness In general, higher speeds should be utilized for parts of smaller diameter.
  • the spinning speed should preferably be of the order of about 1800 R. P. M.
  • the mold may be spun either on a horizontal axis or on a vertical axis, althoughfor large diameter pieces, especially where the wall thickness is relatively great, spinning on a horizontal may vary, it' is preferable that the mold assembly be brought to a temperature appreciably above the melting point of the material to be used.
  • the mold assembly should be brought to a temperature upwards of about 507 F. (the melting point of the adipamide), the temperature being in the range from about 515 F. to about 550 F., and preferably between 520 F. and 535 F. for the larger sizes of 3" O. D. and over, and somewhat higher for the smaller sizes.
  • the mold may, if desired; be flushed prior to charging with an inert gas, such as nitrogen, through the apertured end plug.
  • an inert gas such as nitrogen
  • Theassembly is then placed in a heating chamber such as is shown at 34 in Figure l, wherein the mold may be maintained at whatever temperature is necessary.
  • the heating'chamber 34, with the mold therein, is raised to bring one of the nozzles 32 into the aperture in the end plug.
  • the appropriate valve 33 is then opened and meltedzmaterial isdelive'red into the mold until the desired volume of charge isreached. In theembodiment here axis' is preferred.
  • the material in unmelted form may be charged directly into the mold, in which case the apertured end plug (e. g., 7 in Figure 2) is removed during charging.
  • this apertured plug may be replaced by a plug having a recess not extending through the plug adapted to cooperate with the tapered mold support 22.
  • the mold after being charged with unmelted material, is closed and then heated, as for instance by immersion in a heating bath, to melt the charge.
  • the surface of the bore may lack exact concentricity with the outside surface of the piece. This effect occurs when during. the cooling, the outer layer of material which hardens first remains incontact with the mold at one side whileshrinking out of contact at the other side. Since the inner mass of material is still molten, centrifugal force will hold'the mass in a'positio'n concentric with the axis of rotation. Thus, upon completion of solidification, the.bore which will be concentric with the rotativeaxis', will not beconcentric with the outer surface of'the' molded piece since the outer surface will have having a relatively large-diameter .or a casting having relatively thick walls.
  • a second imperfectionsometimes occurs, that is, the molded piece may bowor bend longitudinally.
  • the cause of this defect is not precisely known. It may result from the use of unbalanced molds. ,It may also result fromthe material remaining in contact with the mold walls unevenly.-Thus, if the material during spinning, solidification and shrinkage, remained against one side of the mold at both ends of the mold while contacting the opposite side of the mold at the middle (longitudinally), then the resultant casting would not be straight sided.
  • the present invention virtually eliminates the above three/defects and makes possible the rapid and accurate molding of cylindrical pieces which are straight, of circular cross section and have concentric inner and outer surfaces. This is accomplished by a mold which places the piece in stress longitudinally as it solidifies and at the 7 same 'time keeps the piece exactly concentric with the rotative axis.
  • the mold cavity extensions at the ends of the. mold have peripheral surfaces which are inclined as shown and when the material being molded undergoes reduction in volume upon solidification, then this longitudinal stress is a tension stress.
  • the mold has a main cavity which molds the main body of the piece and a cavity extension which molds a flared projection on either end of the-piece which will hold the piece centered and tend to place it in tension as it shrinks during solidification.
  • the main mold cavity serves to impart the desired ex- I terior shape to the piece being molded and by centripetal force to contain the molten material during the solidification of a thin outer skin thereof.
  • the piece is suspended by its ends while the gap between the outer surface of the main body of the piece and the mold cavity surface increases.
  • the hardened outer skin of material acts as a mold sustained at its ends and contains the inner mass of material during its solidification.
  • the flared peripheral surface of the mold cavity extension may vary in length and angle of inclination with respect to the rotative axis.
  • the theoretically ideal values of these two variables are related to each other and to the percentage of volumetric shrinkage displayed by the particular material being molded.
  • the maximum diameter of the mold cavity extension should bear a particular relationship to the minimum diameter of saidextension in order to facilitate removal of the piece.
  • the maximum diameter (after shrinkage) of the flared projection molded onto the piece will be approximately the same as the minimum diameter of the mold cavity extension, so that the piece may be snapped out of the mold without necessitating the cutting oif of the flared projection.
  • FIG. 3 wherein is pictured a solidified piece W molded from a material (such as polyhexamethylene adipamide) which displays a volumetric shrinkage upon solidification of approximately 16%.
  • a gap 38 exists between the surface of the main mold cavity and the outside surface of the piece W.
  • the flared projection 39 is just barely “still in contact with the edge 16 of the mold cavity extension .13.
  • the interengagement of the conical flared surfaces of piece W and mold cavity 13 has served to retain the piece W exactly concentric with the rotative axis during the entire solidification and shrinkage.
  • the mold tube 5a has somewhat thicker walls than mold tube 5 but the end plugs 6a and 7a are somewhat thinner than those used with tube 5.
  • the portion of plug 6a which extends into the mold tube is larger in diameter than the inside diameter of the main body of the mold tube.'
  • the edge of the mold interior surface which is adjacent to the inside plug face is chamfered at each end as at 40 and 41.
  • the plug 7a which is adapted to be inserted in the other end of the mold tube is constructed similarly to plug 6a except that the threaded recess is replaced by a central aperture 19a as described above in connection with plug 7.
  • angle of inclination and length of surfaces 40 and 41 may be varied in the manner described in connection with the embodiment shown in Figures 1, 2 and 3.
  • the plugs may advantageously be formed .of a metal having a higher coefficient of thermal expansion than the metal of which the mold enema formed of steel sinus plugs arbmnze;
  • the plugs are also preferably 'carefully machined and finished to a size snugly fitting the end portions of the mold tube when the tube and plugs are at about room temperature. This facilitates insertion and removal of the plugs for the purpose of cleaning the mold tube and also for the purpose of removing cylindrical pieces formed therein.
  • the close fit of the plugs and the diflferenee between coefficients of expansion of the tube and plugs causes the plugs to very tightly close the ends of the mold tube.
  • v v 1 A centrifugal mold for molding a tubular article from molten material characterized by substantial volumetric shrinkage upon solidification, said mold comprising a mold tube and end closure plugs therefor, each of said plugs having an annular groove in the inside face, said groove having anundercut peripheral surface which is flared outwardly in a direction away from the interior of the mold tube.
  • a centrifugal mold according to claim 1 in which said undercut peripheral'surface of the groove is in the form of aright'conic al frustum with the smaller base in communication" with the main cavity, the relationship between the base diameters of said frustum being such that after solidification and shrinkage the material therein has a maximum diameter'approximately equal to the diameter of "said smaller base to thereby ease removal of the piece being molded from said groove.
  • a method for centrifugally molding tubular articles from molten material characterized by substantial volumetric shrinkage upon solidification comprising, rotating a centrifugal mold about its central axis to centrifugally distribute the material, cooling'the mold to solidify a thin layer of the distributed materialin contact with the peripheral wall of the mold, continuing the cooling to thicken said thin layer of solidified material, during which cooling the thickening solidified layer shrinks away from the mold Wall, supporting the thus partially solidified article at its ends by applying circumfer'entially uniformly distributed radial forces thereto and thereby maintaining the peripheral surface of the article concentric with the axis of rotation, and continuing the cooling of the materialandthe rotation thereof in the mold while so supported until the article is completely solidified.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Moulds For Moulding Plastics Or The Like (AREA)
  • Moulding By Coating Moulds (AREA)
US339846A 1950-06-08 1953-03-02 Apparatus and process for centrifugal molding of articles from thermoplastic materials which exhibit substantial volumetric shrinkage Expired - Lifetime US2874412A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
NL99227D NL99227C (xx) 1953-03-02
FR65927D FR65927E (xx) 1950-06-08
FR1047775D FR1047775A (fr) 1950-06-08 1951-06-06 Procédé et dispositifs de moulage
US339846A US2874412A (en) 1953-03-02 1953-03-02 Apparatus and process for centrifugal molding of articles from thermoplastic materials which exhibit substantial volumetric shrinkage
DEP11425A DE1101750B (de) 1953-03-02 1954-03-02 Um ihre horizontale Laengsachse rotierende rohrfoermige Hohlform zum Herstellen von Hohlkoerpern aus organischem Kunststoff nach dem Schleudergiessverfahren

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Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2980966A (en) * 1958-09-29 1961-04-25 Nat Broach & Mach Method of molding a gear finishing tool
US2983961A (en) * 1957-01-30 1961-05-16 Resistoflex Corp Blow molding of polytetrafluoroethylene
US3041699A (en) * 1955-09-23 1962-07-03 Bendix Corp Apparatus for slip-casting ceramic materials
US3184828A (en) * 1962-11-30 1965-05-25 Polymer Processes Inc Roll covers
US3263285A (en) * 1964-07-14 1966-08-02 Black Clawson Co Centrifugal casting apparatus for casting a flanged roll and method of casting
US3290426A (en) * 1964-01-06 1966-12-06 Transpolymer Ind Inc Plastic pipe having a conductive exterior surface and method of making the same
US3437131A (en) * 1965-10-07 1969-04-08 Blaw Knox Co Centrifugal casting apparatus with smooth refractory nonhydrocarbon mold coating
US3604465A (en) * 1967-03-22 1971-09-14 Basler Stueckfaerberei Ag Pipe construction
US3759480A (en) * 1971-04-26 1973-09-18 Catalano Antoinette Two-piece plug for rotational casting process for forming suction cup integral with the molded article
US4034800A (en) * 1974-08-16 1977-07-12 Alexandr Mikhailovich Pavlov Centrifugal plant for producing bimetallic sleeves
US4518342A (en) * 1983-04-11 1985-05-21 Somiver S.R.L. Apparatus for forming centrifuged poles
US5300391A (en) * 1991-09-17 1994-04-05 Xerox Corporation Field assisted processes for preparing imaging members
US5534207A (en) * 1994-07-08 1996-07-09 Natural Resource Recovery, Inc. Method and apparatus for forming an article from recyclable plastic materials
US5538678A (en) * 1992-04-30 1996-07-23 Sony Corporation Method for molding a cassette
US5702656A (en) * 1995-06-07 1997-12-30 United States Surgical Corporation Process for making polymeric articles
US6176698B1 (en) * 1998-02-24 2001-01-23 Medtronic Ave, Inc. Thin cone balloons through a unique mold design
US20040238982A1 (en) * 2003-05-28 2004-12-02 Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd) Method for producing glass-like carbon pipe, and glass-like carbon pipe produced by such method
EP2086734A1 (en) * 2006-11-03 2009-08-12 R&D Green Materials, LLC Process for preparing biodegradable articles

Families Citing this family (1)

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Publication number Priority date Publication date Assignee Title
DE1778265B1 (de) * 1968-04-13 1972-05-31 Schoenebecker Brunnenfilter Gm Verfahren und Vorrichtung zum gleichmaessigen Beschicken einer zum Herstellen von Rohren und aehnlichen Hohlformen im Schleuder-verfahren dienenden Rohrform mit teigartigen Massen aus fluessigen oder geloesten Kunststoffen

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US1642199A (en) * 1927-01-24 1927-09-13 Spiegel May Stern Company Method of making inking pads
US1678633A (en) * 1923-12-17 1928-07-31 Centrifugal Pipe Corp Casting pipe
US2349549A (en) * 1941-04-24 1944-05-23 Herbert V Hardman Method of making depolymerized rubber articles
US2462821A (en) * 1945-01-22 1949-02-22 Sk Wellman Co Method of making composite articles
US2518504A (en) * 1947-06-17 1950-08-15 Polymer Corp Method for fabricating nylon bushings

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GB475552A (en) * 1936-05-18 1937-11-18 Roehm & Haas Ag Improvements in and relating to the manufacture of polymerisation products

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1678633A (en) * 1923-12-17 1928-07-31 Centrifugal Pipe Corp Casting pipe
US1642199A (en) * 1927-01-24 1927-09-13 Spiegel May Stern Company Method of making inking pads
US2349549A (en) * 1941-04-24 1944-05-23 Herbert V Hardman Method of making depolymerized rubber articles
US2462821A (en) * 1945-01-22 1949-02-22 Sk Wellman Co Method of making composite articles
US2518504A (en) * 1947-06-17 1950-08-15 Polymer Corp Method for fabricating nylon bushings

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3041699A (en) * 1955-09-23 1962-07-03 Bendix Corp Apparatus for slip-casting ceramic materials
US2983961A (en) * 1957-01-30 1961-05-16 Resistoflex Corp Blow molding of polytetrafluoroethylene
US2980966A (en) * 1958-09-29 1961-04-25 Nat Broach & Mach Method of molding a gear finishing tool
US3184828A (en) * 1962-11-30 1965-05-25 Polymer Processes Inc Roll covers
US3290426A (en) * 1964-01-06 1966-12-06 Transpolymer Ind Inc Plastic pipe having a conductive exterior surface and method of making the same
US3263285A (en) * 1964-07-14 1966-08-02 Black Clawson Co Centrifugal casting apparatus for casting a flanged roll and method of casting
US3437131A (en) * 1965-10-07 1969-04-08 Blaw Knox Co Centrifugal casting apparatus with smooth refractory nonhydrocarbon mold coating
US3604465A (en) * 1967-03-22 1971-09-14 Basler Stueckfaerberei Ag Pipe construction
US3759480A (en) * 1971-04-26 1973-09-18 Catalano Antoinette Two-piece plug for rotational casting process for forming suction cup integral with the molded article
US4034800A (en) * 1974-08-16 1977-07-12 Alexandr Mikhailovich Pavlov Centrifugal plant for producing bimetallic sleeves
US4518342A (en) * 1983-04-11 1985-05-21 Somiver S.R.L. Apparatus for forming centrifuged poles
US5300391A (en) * 1991-09-17 1994-04-05 Xerox Corporation Field assisted processes for preparing imaging members
US5538678A (en) * 1992-04-30 1996-07-23 Sony Corporation Method for molding a cassette
US5534207A (en) * 1994-07-08 1996-07-09 Natural Resource Recovery, Inc. Method and apparatus for forming an article from recyclable plastic materials
US5702656A (en) * 1995-06-07 1997-12-30 United States Surgical Corporation Process for making polymeric articles
US6176698B1 (en) * 1998-02-24 2001-01-23 Medtronic Ave, Inc. Thin cone balloons through a unique mold design
US20040238982A1 (en) * 2003-05-28 2004-12-02 Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd) Method for producing glass-like carbon pipe, and glass-like carbon pipe produced by such method
US7311863B2 (en) * 2003-05-28 2007-12-25 Kobe Steel, Ltd. Method for producing glass-like carbon pipe, and glass-like carbon pipe produced by such method
EP2086734A1 (en) * 2006-11-03 2009-08-12 R&D Green Materials, LLC Process for preparing biodegradable articles
EP2086734A4 (en) * 2006-11-03 2011-05-04 R & D Green Materials Llc PROCESS FOR PREPARING BIODEGRADABLE ARTICLES

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DE1101750B (de) 1961-03-09

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